Micro Motion MICRO MOTION 2-WIRE TPS GDM INSTALLATION SUPPLEMENT Manuals & Guides

Installation Manual

MMI-20031634, Rev AA

December 2016

Micro Motion® 2-Wire Time Period Signal (TPS)
Gas Density Meter (GDM)

2-Wire TPS GDM Installation Supplement

Safety and approval information

This Micro Motion product complies with all applicable European directives when properly installed in accordance with the
instructions in this manual. Refer to the EC declaration of conformity for directives that apply to this product. The EC declaration of
conformity, with all applicable European directives, and the complete ATEX Installation Drawings and Instructions are available on
the internet at www.micromotion.com or through your local Micro Motion support center.

For information about the Pressure Equipment Directive, go to www.micromotion.com/documentation.

For hazardous installations in Europe, refer to standard EN 60079-14 if national standards do not apply.

Other information

Full product specifications can be found in the product data sheet. Troubleshooting information can be found in the configuration
manual. Product data sheets and manuals are available from the Micro Motion web site at www.micromotion.com/documentation.

Return policy

Follow Micro Motion procedures when returning equipment. These procedures ensure legal compliance with government
transportation agencies and help provide a safe working environment for Micro Motion employees. Micro Motion will not accept
your returned equipment if you fail to follow Micro Motion procedures.

Return procedures and forms are available on our web support site at www.micromotion.com, or by phoning the Micro Motion
Customer Service department.

Emerson Flow customer service

Email:

• Worldwide: [e-mail]

• Asia-Pacific: [e-mail]

Telephone:

North and South America Europe and Middle East Asia Pacific

United States 800-522-6277 U.K. 0870 240 1978 Australia 800 158 727

Canada [phone] The Netherlands [phone] New Zealand 099 128 804

Mexico [phone] France 0800 917 901 India 800 440 1468

Argentina [phone] Germany 0800 182 5347 Pakistan 888 550 2682

Brazil [phone] Italy 8008 77334 China [phone]

Venezuela [phone] Central & Eastern [phone] Japan [phone]

Russia/CIS [phone] South Korea [phone]

Egypt 0800 000 0015 Singapore [phone]

Oman 800 70101 Thailand 001 800 441 6426

Qatar 431 0044 Malaysia 800 814 008

Kuwait 663 299 01

South Africa 800 991 390

Saudi Arabia 800 844 9564

UAE 800 0444 0684

Contents

Contents

Chapter 1 Planning ........................................................................................................................ 1

1.1 2-wire installations .......................................................................................................................1

1.2 Installation checklist .................................................................................................................... 1

1.3 Best practices .............................................................................................................................. 2

1.4 Recommended sample flow rate ................................................................................................. 3

1.5 Power requirements .................................................................................................................... 4

1.6 Installation requirements for the thermo-well pocket ..................................................................7

1.7 Recommended installations for gas density applications ............................................................. 8

1.8 Perform a pre-installation meter check ...................................................................................... 14

Chapter 2 Mounting .....................................................................................................................16

2.1 Mount the meter in the pipeline ................................................................................................ 16

2.2 Connect the gas bypass lines ..................................................................................................... 18

2.3 Rotate the electronics on the meter (optional) .......................................................................... 20

2.4 Post-installation check ...............................................................................................................20

Chapter 3 Wiring ......................................................................................................................... 21

3.1 Terminals and wiring requirements ............................................................................................21

3.2 Hazardous area output wiring ....................................................................................................22

3.3 Wire to galvanic isolators ...........................................................................................................28

Chapter 4 Grounding ....................................................................................................................30

Chapter 5 Verifying ...................................................................................................................... 31

5.1 Verify the meter .........................................................................................................................31

5.2 Meter health tests ......................................................................................................................31

Appendices and reference

Appendix A Sample calibration certificate .......................................................................................33

Installation Manual i

Contents

ii Micro Motion Gas Density Meter

1 Planning

Topics covered in this chapter:

2-wire installations

•

Installation checklist

•

Best practices

•

Recommended sample flow rate

•

Power requirements

•

Installation requirements for the thermo-well pocket

•

Recommended installations for gas density applications

•

Perform a pre-installation meter check

•

1.1 2-wire installations

Planning

1.2

The 2-wire Time Period Signal (TPS) is a configuration option available on the Gas Density
Meter (GDM).

This option provides:

• A TPS output superimposed on the same pair of wires used to power the meter

• An optional 4-wire connection to the internal RTD

Restriction

The 2-wire TPS device does not support:

• Internal calculations of density

• Integral health diagnostics, alarm and alert statuses, or internal calculation of other

measurement variables derived from gas density

• The display option

Installation checklist

□

Verify the contents of the product shipment to confirm that you have all parts and
information necessary for the installation.

Part

Micro Motion® Gas Density Meter (GDM) 1

Installation Manual 1

Quantity

Planning

Part Quantity

Accessories kit:

- M20 to 1/2-inch NPT adapter (if applicable)

- 1/2-inch NPT blanking plug

- 2.5 mm hex key

Aluminum sleeve 1

Silicon fluid 1

Thermo-well pocket kit (if applicable) 1

Calibration certificate 1

Safety instructions booklets 2

Micro Motion Product Documentation DVD 1

□

Make sure that all electrical safety requirements are met for the environment in
which the meter will be installed.

□

Make sure that the local ambient and process temperatures and process pressure
are within the limits of the meter.

□

Make sure that the hazardous area specified on the approval tag is suitable for the
environment in which the meter will be installed.

□

If installing the meter in a hazardous area, confirm that you have the required safety
barriers or galvanic isolators for your installation.

□

Make sure that you will have adequate access to the meter for verification and
maintenance.

□

Make sure that the process gas meets the recommended characteristics regarding
composition, temperature, and pressure for your installation.

□

Verify that you have all equipment necessary for your installation. Depending on
your application, you may be required to install additional parts for optimal
performance of the meter.

□

Follow recommended best practices for installing the GDM to account for the
effects of density, temperature, and pressure equilibrium.

1

1.3

2 Micro Motion Gas Density Meter

Best practices

The following information can help you get the most from your meter.

• Handle the meter with care. Follow local practices for lifting or moving the meter.

• Ensure that the process gas is clean and dry.

• Do not use gases incompatible with the materials of construction. To prevent

corrosion of the sensing element, the process gas should be compatible with
Ni-Span-C.

• Do not expose the meter to excessive vibration (greater than 0.5 g continuously).

Vibration levels in excess of 0.5 g can affect the meter accuracy.

Planning

• Installing the meter in a bypass configuration allows you to remove the meter for

servicing or calibration without affecting the main pipeline.

• Install the meter in a thermo-well pocket to ensure the temperature of the sample

gas is equal to that of the pipeline gas. Micro Motion thermo-well pocket kits are
available for purchase.

• Minimize the length and volume of the input sample pipe to ensure an optimal

meter response time. Use 6 mm (1/4 in) instrument tubing and low-volume inlet
filters.

• Control gas flow with a needle valve mounted before or after the meter, depending

on the installation.

• Install an external coalescing filter in the sample gas inlet pipework to minimize

condensate and dust contamination.

• Verify that the filters in your system are not causing any excessive flow restrictions.

• Verify that the pressure of the process gas is approximately equal to the pipeline

pressure.

• Ensure that the meter and associated pipework are pressure-tested to 1½ times the

maximum operating pressure after installation.

• Install thermal insulation to the meter and the inlet and bypass-loop pipeline to

maintain temperature equilibrium between the sample and pipeline gases. Do not
insulate the transmitter (electronics) and maintain a nominal 1-in clearance
between the insulation and the transmitter housing.

1.4

Recommended sample flow rate

Use the smallest acceptable flow rate for the process gas passing through the meter. This
ensures a sample gas flow rate that is representative of the main flow with regard to the
proportions of different gas constituents.

Micro Motion recommends a gas flow rate of 5 ±1 l/hr (0.176 ±0.35 ft3/hr), although a flow
rate between 1 to 10 l/hr (0.035 to 0.35 ft3/hr) is acceptable.

At flow rates greater than 10 l/hr (0.35 ft3/hr), the density reading can become slightly
unstable and may introduce a small density error. For natural gas with a typical application
density of approximately 0.06 g/cm3 (60 kg/m3), a pressure differential of approximately

1.66 mbar (0.67 in WC) is required to maintain a flow rate of 5 l/hr (0.176 ft3/hr) .

Installation Manual 3

Volume of gas in meter = 40 cm

3

3.5

3

2.5

2

1.5

1

.5

0

0 2 4 6 8 10

Flowrate (lt/hr)

Recommended
operating
flow rate

Volume of gas in meter = 2.44 in

3

1.2

1.0

.8

.6

.4

.2

0

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Flowrate (ft3/hr)

Pressure drop (mbar)

Pressure drop (inch WC)

Recommended
operating
flow rate

Planning

Pressure drop through the meterFigure 1-1:

1.5 Power requirements

The following DC power requirements are needed to operate the meter:

• 24 VDC, 0.25 W typical with 300 Ω barrier, 0.3 W maximum with 300 Ω barrier

• Minimum recommended voltage: 22.8 VDC with 1000 ft of 22 AWG (300 m of 0.25

mm2) power-supply cable with 300 Ω barrier

4 Micro Motion Gas Density Meter

Power cable recommendations for intrinsically-safe meters

Minimum wire gauge with 300 Ω barrierFigure 1-2:

Planning

A. AWG
B. Distance of installation in feet

Installation Manual 5

Planning

Minimum wire area with 300 Ω barrierFigure 1-3:

A. Minimum wire area (mm2)
B. Distance of installation in meters

6 Micro Motion Gas Density Meter

Planning

Limits of series resistance versus supply voltageFigure 1-4:

1.6

A. Series resistance (Ω)
B. Supply voltage (V)
C. 300 Ω barrier resistance
D. Normal operating point
E. Maximum resistance for correct operation
F. Minimum resistance for 5 volt TPS
G. The 2-wire GDM fully operates anywhere in the shaded area

Installation requirements for the thermo-well pocket

Installation of the GDM in a thermo-well pocket helps maintain temperature equilibrium
between the sample gas and pipeline gas. Micro Motion provides thermo-well pocket
installation kits for purchase. Contact your local sales representative or Micro Motion
Customer Support at [e-mail] for more information.

A thermo-well pocket installation requires the following, before you can mount and
connect the GDM:

1. Create an aperture in the pipeline to receive the pocket (see Figure 1-5 for the pocket
dimensions).

2. Install and weld the pocket in place. Be sure to follow local practices and guidelines
for welding in hazardous areas, if applicable.

Installation Manual 7

6.00

(152.30)

Ø3.94

(100.00)

1.59

(40.30)

2.83

(72.00)

Dimensions in

inches
(mm)

Planning

Micro Motion thermo-well pocket dimensionsFigure 1-5:

1.7 Recommended installations for gas density applications

Micro Motion recommends specific installations for the GDM depending on the gas
density application – as defined by international standards, ISO 5167 and AGA 3. This
information is provided for your reference only.

1.7.1

8 Micro Motion Gas Density Meter

Installation in an orifice plate metering system

The orifice plate metering system is a widely used method for accurate flow measurement
of natural gas. The orifice meter is a differential pressure device in which the orifice plate
causes a pressure drop between the upstream and downstream sides. The flow rate is
determined from the dimensions of the system (as defined by international standards ISO
5167 and AGA 3), and from measurements of differential pressure and fluid density.

Meter installation in a pressure recovery application

The most common location for a density device in an orifice plate metering system is
downstream from the orifice plate. This installation is commonly referred to as the
pressure recovery method. The pressure recovery method allows an optimal gas flow rate,
and provides easy access for checking filters and verifying the meter calibration.

Tip

Use 6-mm (1/4-in) instrument tubing for the gas input pipework. Use 12-mm (1/2-in) insertion
tubing for the gas return pipework.

Meter installation in pressure recovery applicationFigure 1-6:

Planning

A. Meter isolation valves
B. Flowmeter
C. Venting valve
D. Flow control needle valve
E. Filter
F. Pipeline diameter
G. Differential pressure transmitter
H. Density point
I. Distance is eight times the pipeline diameter
J. Thermal insulation
K. Vent/vacuum test point

Note

Do not insulate the transmitter (electronics) and maintain a nominal 1-in clearance between the insulation and the transmitter
housing.

With the pressure recovery installation method:

Installation Manual 9

Planning

• No bypass of the orifice plate is necessary.

• Density is measured at the downstream tapping of the orifice plate, which reduces

the significance of pressure build-up across the fine-gauge filters.

• Flow is achieved because the pressure after the orifice plate is lower than that

further downstream.

• Pressure drops through the valves and filters do not affect the reading. The pressure

inside the meter and at the gas outlet is equal to the pressure at the orifice
downstream point.

• The correct expansion factor for the downstream point is used in the orifice flow

calculations.

• The measured density at the density point is used in the mass flow calculation, as

defined by ISO 5167 and AGA 3.

Meter installation in differential pressure application

An alternative to the downstream installation method is the upstream installation method,
as defined by AGA 3. This method is also known as the differential pressure method, which
is optimal for orifice plate metering. A disadvantage of this installation is that the sample
gas flow is not measured because it bypasses the orifice plate.

10 Micro Motion Gas Density Meter

Planning

Meter installation in differential pressure applicationFigure 1-7:

A. Meter isolation valves
B. Flowmeter
C. Venting valve
D. Flow control needle valve
E. Filter
F. Differential pressure transmitter
G. Thermal insulation
H. Vent/vacuum test point

Note

Do not insulate the transmitter (electronics) and maintain a nominal 1-in clearance between the insulation and the transmitter
housing.

With the differential pressure installation method:

• The process gas flow bypasses the meter, but should be low enough [for example,

5 lt/hrs (0.176 ft3/hr)] to not be of significance.

• The measured density is the upstream density.

• The control valve and the flowmeter can be mounted on either side of the meter to

suit the installation and dependent on where the density point is.

Tip

To avoid excessive pressure drops in your sample pipeline, be sure to monitor the condition of the
filters. Do this by varying the sample flow rate and monitoring the magnitude of the resultant density
changes. Pressure drops through the filters can cause density errors if they become too large.

Installation Manual 11

Planning

1.7.2 Meter installation in a vented gas application

The vented gas method allows the gas to be vented to flare or, in some cases, to
atmosphere. With this method, the full-pipe pressure is available as a pressure drop. For
high-pressure applications, a two-stage letdown system may be required to prevent icing.

CAUTION!

Because the full-pipe pressure is available as a pressure drop, ensure that the flow is
adequately controlled by the control valve.

Meter installation in a vented gas applicationFigure 1-8:

A. Meter isolation valves
B. Flowmeter
C. Venting valve
D. Flow control needle valve
E. Filter
F. Pressure regulator
G. Thermal insulation
H. Vent/vacuum test point
I. Low-pressure vent system connection point

Note

Do not insulate the transmitter (electronics) and maintain a nominal 1-in clearance between the insulation and the transmitter
housing.

12 Micro Motion Gas Density Meter

1.7.3 Meter installation in an ultrasonic meter application

To use the GDM with a full-bore ultrasonic meter, Micro Motion recommends that you
install an insertion probe downstream from the ultrasonic meter as a means to provide
differential pressure.

The following diagram shows an insertion probe installed to provide differential pressure
for the measurement system. This type of installation method does not require sample gas
to be vented to atmosphere. The insertion probe and GDM must be installed a specific
distance downstream from the ultrasonic meter in your pipeline. Refer to all manufacturer
guidelines for best practices or recommendations for installing the meters in your system.

Meter installation in an ultrasonic meter applicationFigure 1-9:

Planning

A. Meter isolation valves
B. Flowmeter
C. Venting valve
D. Flow control needle valve
E. Filter
F. Insertion probe
G. Thermal insulation
H. Vent/vacuum test point

Note

Do not insulate the transmitter (electronics) and maintain a nominal 1-in clearance between the insulation and the transmitter
housing.

Installation Manual 13

Planning

1.7.4 Meter installation with a turbine flow meter

The following diagram shows a meter measurement system with a gas turbine flowmeter
installation. Refer to manufacturer guidelines for best practices or recommendations for
installing the meter in your system.

Meter installation with a turbine flow meterFigure 1-10:

A. Meter isolation valves
B. Flowmeter
C. Venting valve
D. Flow control needle valve
E. Filter
F. Turbine flowmeter
G. Thermal insulation
H. Vent/vacuum test point

Note

Do not insulate the transmitter (electronics) and maintain a nominal 1-in clearance between the insulation and the transmitter
housing.

1.8

Perform a pre-installation meter check

1. Remove the meter from the box.

CAUTION!

Handle the meter with care. Follow all corporate, local, and national safety regulations
for lifting and moving the meter.

14 Micro Motion Gas Density Meter

2. Visually inspect the meter for any physical damage.

If you notice any physical damage to the meter, immediately contact Micro Motion
Customer Support at [e-mail].

3. Position and secure the meter in a vertical position with the flow arrow pointing

upward.

4. Connect the power wiring, and power up the meter.

Remove the back transmitter housing cover to access the PWR terminals.

Planning

A. RTD connector block
B. Chassis ground (external)
C. Chassis ground (internal)
D. Power/TPS connector block

5. Perform a verification check.

Related information

Verify the meter

Installation Manual 15

Mounting

2 Mounting

Topics covered in this chapter:

Mount the meter in the pipeline

•

Connect the gas bypass lines

•

Rotate the electronics on the meter (optional)

•

Post-installation check

•

2.1 Mount the meter in the pipeline

Prerequisites

Important

Micro Motion recommends that you install the meter in a thermo-well pocket to maintain
temperature equilibrium between the sample gas and the pipeline gas. For ease of maintenance, you
can insert and remove the meter from the pocket as needed. See Section 1.6 for more information on
the pocket installation.

The following parts are recommended for installation in a pipeline.

• Micro Motion ® Gas Density Meter (GDM)

• Thermo-well pocket kit, which includes:

- Thermo-well pocket

- Anti-vibration gaskets

- Aluminum sleeve

- Silicone fluid

- Mounting screws

16 Micro Motion Gas Density Meter

Mounting

Meter installation piecesFigure 2-1:

A. M8 socket-head cap screw (for mounting)
B. Meter housing
C. Aluminum sleeve (cylinder)
D. Anti-vibration gasket
E. Thermo-well pocket

Procedure

1. (Recommended) Install the thermo-well pocket in the aperture created in the

pipeline and weld it into place.

2. Pour the supplied silicon fluid (an amount of 20 cm3) into the interior of the pocket.

3. Place one 5-mm anti-vibration gasket on top of the pocket.

Align the anti-vibration gasket holes with the bolt holes on the pocket.

4. Place the aluminum sleeve over the end of the meter housing.

5. Insert the meter housing into the pocket.

6. Secure the meter into place, using the supplied mounting screws.

Installation Manual 17

Mounting

Typical installation in pipeline (with thermo-well pocket)Figure 2-2:

Dimensions are in inches.

2.2 Connect the gas bypass lines

Once you have mounted the meter in the pipeline, you are ready to connect the gas
bypass lines.

Adjacent to the gas connection ports, the meter provides two filters to ensure optimal
performance of the meter sensing element.

• 2 micron filter for the inlet connection

• 90 micron filter for the outlet connection

The outlet filter provides additional protection if reverse gas flow occurs. This filter
arrangement is best suited for density measurement at the process gas return point.

Procedure

Connect the process gas bypass lines to the gas inlet/outlet ports.

18 Micro Motion Gas Density Meter

Mounting

Gas inlet/outlet connectorsFigure 2-3:

A. Process gas outlet
B. Process gas inlet
C. Filter

Installation Manual 19

A

Mounting

2.3 Rotate the electronics on the meter (optional)

You can rotate the transmitter on the meter up to 90°.

1. Using a 4 mm hex key, loosen the cap screw that holds the transmitter in place.

Component to secure transmitter in placeFigure 2-4:

2.4

A. M5 socket-head cap screw

2. Rotate the transmitter clockwise to the desired orientation up to 90°.

3. Secure the cap screw in place and tighten to 60 lb·in (6.8 N·m).

Post-installation check

After you complete the installation of the meter, pressure test the meter and associated
pipework to 1½ times the maximum operating pressure.

20 Micro Motion Gas Density Meter

3 Wiring

Topics covered in this chapter:

Terminals and wiring requirements

•

Hazardous area output wiring

•

Wire to galvanic isolators

•

3.1 Terminals and wiring requirements

Three pairs of wiring terminals are available for transmitter outputs. One terminal is
designated for the 24 VDC Power and Time Period Signal (TPS). The other two terminals
are for the internal RTD connection.

The screw connectors for each output terminal accept a maximum wire size of 14 AWG
(2.5 mm2).

Wiring

Important

Output wiring requirements depend on whether the meter will be installed in a safe area or a
hazardous area. It is your responsibility to verify that this installation meets all corporate, local, and
national safety requirements and electrical codes.

Installation Manual 21

Wiring

Output wiring terminalsFigure 3-1:

3.2

A. RTD connector block
B. Chassis ground (external)
C. Chassis ground (internal)
D. Power/TPS connector block

Hazardous area output wiring

Micro Motion provides safety barrier installation kits for wiring the meter in a hazardous
environment. These kits provide the appropriate barriers depending on the outputs
available and approvals required.

Information provided about wiring the safety barriers is intended as an overview. You
should wire the meter according to the standards that are applicable at your site.

CAUTION!

• Meter installation and wiring should be performed by suitably trained personnel only in

accordance with the applicable code of practice.

• Refer to the hazardous area approvals documentation shipped with your meter. Safety

instructions are available on the Micro Motion Product Documentation DVD and
accessible on the Micro Motion website at www.micromotion.com.

22 Micro Motion Gas Density Meter

3.2.1 Hazardous area entity parameters

DANGER!

• Hazardous voltage can cause severe injury or death. To reduce the risk of hazardous

voltage, shut off power before wiring the meter.

• Improper wiring in a hazardous environment can cause an explosion. Install the meter

only in an area that complies with the hazardous classification tag on the meter.

Input entity parameters

Power in/signal output terminals 1, 2Table 3-1:

Parameter

Maximum input voltage Ui 28 V

Maximum input current li 93 mA

Maximum input power Pi 0.65 W

Maximum internal capacitance Ci 0 nF

Maximum internal inductance Li 0 mH

Wiring

RTD terminals 5, 6, 7 and 8Table 3-2:

Parameter

Maximum input voltage Ui 12 V

Maximum input current li 36 mA

Maximum input power Pi 0.432 W

Maximum internal capacitance Ci 0 nF

Maximum internal inductance Li 0 mH

The voltage, current, and power values are the total available to all four RTD connections.

The total inductance (La) and capacitance (Ca) allowable for the electronics plus the cable
connecting it to the Zener barriers must be equal or less than the specified values for the
hazardous are classification. Refer to the hazardous area approvals documentation
shipped with the meter.

Hazardous area
capacitance

The capacitance (Ci) of the meter is 0.0 µF. There is no extra
capacitance when calculating the maximum capacitance allowable for
the connecting cable. Therefore, the cable capacitance may be less or
equal to the maximum permitted capacitance (Ca) specified by the
safety barrier: (Ccable ≤ Ca)

Installation Manual 23

Wiring

Hazardous
area
inductance

The inductance (Li) of the meter is 0.0 µH. There is no extra inductance
when calculating the maximum inductance allowable for the
connecting cable. Therefore, the cable inductance may be less or equal
to the maximum permitted inductance (La) specified by the safety
barrier: (Lcable ≤ La)

3.2.2 Wire all intrinsically-safe installations using Zener safety barriers

Micro Motion provides safety barriers for wiring the meter in a hazardous area. Contact
your local sales representative or Micro Motion Customer Support at

[e-mail] for more information on ordering the appropriate barriers.

CAUTION!

• Install the meter installation and wiring only if you are suitably trained in accordance

with the applicable code of practice.

• Refer to the hazardous area approvals documentation shipped with your meter. Safety

instructions are available on the Micro Motion Product Documentation DVD and
accessible on the Micro Motion website at www.micromotion.com.

• Wire the i.s. barrier earth directly to its own earth bar as described in the safety

instructions. If you do not have a good i.s. earth — for example, if you are installing the
meter in a dry area, then use galvanic isolators instead of Zener safety barriers. Order
galvanic isolators from an external supplier since Micro Motion does not sell them.

The barriers are used for connecting all of the available meter outputs. Use the following
barriers with the designated output.

Output(s)

Power and TPS MTL 7787+ BARRIER7787

RTD MTL 7764+ (two) BARRIER7764

Barrier Model code for ordering

Procedure

Using the 2-wire wiring diagrams, wire the barriers to the appropriate output terminal and
pins.

24 Micro Motion Gas Density Meter

Wiring

2-wire wiring diagrams

CAUTION!

• To meet the EC Directive for Electromagnetic Compatibility (EMC), use a suitable

instrumentation cable to connect the meter. The instrumentation cable should have
individual screens, foil or braid over each twisted pair, and an overall screen to cover all
cores. Where permissible, connect the overall screen to earth at both ends (360° bonded
at both ends). Connect the inner individual screens at only the controller end.

• Use metal cable glands where the cables enter the meter amplifier box. Fit unused cable

ports with metal blanking plugs.

Minimum 2-wire barrier connectionFigure 3-2:

A. Power / TPS out
B. IS barrier earth bar
C. IS ground
D. TPS signal +
E. TPS signal –

Installation Manual 25

Wiring

2-wire barrier connection with flow computer / signal converterFigure 3-3:

The following figure describes a 2-wire barrier connection that is powered through a flow computer /
signal converter.

A. Power / TPS out
B. IS barrier earth bar
C. IS ground
D. Flow computer / signal converter
E. Power +
F. TPS signal +
G. Power –
H. TPS signal –

26 Micro Motion Gas Density Meter

Wiring

2-wire barrier connection plus RTD barrier connectionFigure 3-4:

A. Power / TPS out
B. IS barrier earth bar
C. RTD
D. Flow computer / signal converter
E. Power +
F. TPS signal +
G. Power –
H. TPS signal –
I. RTD supply +
J. RTD signal +
K. RTD signal –
L. RTD supply –

Installation Manual 27

Wiring

M. IS ground

Note

If required, use two separate screened cables via two separate cable glands, one for the power and
one for the RTD. However, Micro Motion recommends that you use a single cable to facilitate a good
seal through a single cable entry gland.

3.3 Wire to galvanic isolators

In hazardous area installations where there is no proper I.S. ground available, such as dry
locations, Micro Motion recommends that you use galvanic isolators instead of Zener
barriers. Galvanic isolators convert the signal differently from Zenier barriers when passing
the signal across an isolation gap.

Prerequisites

• Galvanic isolators (MTL5532 and MTL5575)

Note

Micro Motion does not sell galvanic isolators. Obtain the isolators from an external supplier.

• A Zener diode

The MTL5532 pulse isolator has a trigger level connected to the power + pin that is
not connected to the power – pin. Therefore, a Zener diode ensures a reliable
switching point.

• A pull-up resistor

The resistor is required because the output is passive.

• A 20 V to 35 V supply on the safe area side.

The MTL5575 is used specifically for the 4-wire RTD, and converts the RTD voltage and
current into a 4-20mA loop signal on the safe area side. The isolator requires 20 V to 35 V
DC energization from the safe area side that also supplies the active output of the 4-20 mA
loop.

Procedure

Using the 2-wire galvanic isolator wiring diagram, wire the isolators to the appropriate
output terminal and pins.

28 Micro Motion Gas Density Meter

Wiring

2-wire galvanic isolator connectionsFigure 3-5:

A. Hazardous area
B. Safe area
C. Flow computer / signal converter
D. Power +
E. Power –
F. TPS signal +
G. TPS signal –
H. Analog i/p +
I. Analog i/p –
J. Analog pwr +
K. Analog pwr –

Note

Connect the screens to the chassis if no better earth is available.

Isolator trip level switch setting

12 V 6.2 V

6 V 13 V

3 V 16 V

Zener voltage

Installation Manual 29

Grounding

4 Grounding

The meter must be grounded according to the standards that are applicable at the site.
The customer is responsible for knowing and complying with all applicable standards.

Prerequisites

Micro Motion suggests the following guides for grounding practices:

• In Europe, EN 60079-14 is applicable to most installations, in particular Sections

12.2.2.3 and 12.2.2.4.

• In the U.S.A. and Canada, ISA 12.06.01 Part 1 provides examples with associated

applications and requirements.

• For IECEx installations, IEC 60079-14 is applicable.

If no external standards are applicable, follow these guidelines to ground the meter:

• Use copper wire, 18 AWG (0.75 mm2) or larger wire size.

• Keep all ground leads as short as possible, less than 1 Ω impedance.

• Connect ground leads directly to earth, or follow plant standards.

CAUTION!

Ground the meter to earth, or follow ground network requirements for the facility. Improper
grounding can cause measurement error.

Procedure

Check the joints in the pipeline.

- If the joints in the pipeline are ground-bonded, the sensor is automatically grounded

and no further action is necessary (unless required by local code).

- If the joints in the pipeline are not grounded, connect a ground wire to the grounding

screw located on the sensor electronics.

30 Micro Motion Gas Density Meter

5 Verifying

Topics covered in this chapter:

Verify the meter

•

Meter health tests

•

5.1 Verify the meter

Use the following procedure after installation to verify that your meter is working
correctly.

1. Check for a series resistance of approximately 300 Ω either as a load resistor or the

Zener barrier.

2. Measure the current consumption and the supply voltage at the meter terminals.

3. Verify that the measured values match the values in the following table.

Verifying

Power supply voltage (safe
area)

22.8 VDC 18.4 ± 0.5 VDC 13.6 mA ± 0.7 mA

24.0 VDC 20.0 ± 0.5 VDC 12.4 mA ± 0.7 mA

28.0 VDC 24.9 ± 0.5 VDC 9.8 mA ± 0.7 mA

5.2 Meter health tests

To verify the health of the GDM, perform one or more of the following tests. Use your local
corporate procedures to perform these tests.

Ambient air test

To validate the health of the GDM under ambient conditions, compare the values in the
calibration certificate against the time period output signal that corresponds to the
density of the ambient air.

The accuracy of this test depends on the density span of the GDM, and known conditions
of the ambient air. The following table shows the typical change in air density with
ambient conditions.

GDM terminal voltage (haz­ardous area) Supply current

Installation Manual 31

Verifying

Air density changesTable 5-1:

Air pressure (mm Hg) Density at 10 °C (kg/m

790 1.294 1.247

760 1.224 1.199

730 1.195 1.152

3

Density at 20 °C (kg/m

3

Atmospheric pressure test

An atmospheric pressure test measures the density of the gas inside the GDM at
atmospheric conditions. This test can be used to compare against a known reference
density value. You can isolate the GDM from the gas pipeline by closing the shut off valves.
Slowly vent the gas in the GDM to atmosphere. If the initial gas pressure is high, vent
slowly in order to prevent cooling due to gas expansion.

Vacuum test point

A vacuum test point checks the zero density point.

This is the most accurate of the three tests, and is run by isolating the GDM from the gas
pipeline and then evacuating the sensing chamber using a conventional vacuum pump
(less than 1 mmHg). The advantage of using this test is that the GDM temperature and the
gas composition are of little significance.

Note

The zero density test result will not give a zero indication when using the calibration factors from the
GDM. Run the test against the “Verification Time Period (Vacuum) @ 20 °C” listed on the calibration
certificate.

The vacuum test does not check instrument sensitivity. It is not possible to change the
instrument sensitivity without also changing its zero point unless the spoolbody has aged
badly or been replaced.

An agreement of ±0.015μs, (equivalent to 0.007 kg/m3) taking into account a
temperature effect of 0.02μs per °C, should be considered a “pass” result, and indicates
the GDM is in good health. If the GDM does not meet this criteria during a vacuum test,
please contact your local Emerson or Micro Motion Sales and Technical Support team for
further guidance. The sound velocity of the gas will also change the instrument sensitivity,
but this is accounted for when generating an instrument calibration certification and will
only become apparent when changing from one gas type to another.

32 Micro Motion Gas Density Meter

Appendix A
Sample calibration certificate

Your meter was shipped with a calibration certificate. The calibration certificate describes
the calibrations and configurations that were performed or applied at the factory.

Sample calibration certificate: 2-wire TPS GDMFigure A-1:

Sample calibration certificate

Installation Manual 33

Micro Motion Inc. USA

Worldwide Headquarters
7070 Winchester Circle
Boulder, Colorado 80301
T [phone]
T [phone]
F [phone]

www.micromotion.com

Micro Motion Europe

Emerson Automation Solutions
Neonstraat 1
6718 WX Ede
The Netherlands
T [phone]
F [phone]

www.micromotion.nl

*MMI-20031634*

MMI-20031634

Rev AA

2016

Micro Motion Asia

Emerson Automation Solutions
1 Pandan Crescent
Singapore 128461
Republic of Singapore
T [phone]
F [phone]

Micro Motion United Kingdom

Emerson Automation Solutions
Emerson Process Management Limited
Horsfield Way
Bredbury Industrial Estate
Stockport SK6 2SU U.K.
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Micro Motion Japan

Emerson Automation Solutions
1-2-5, Higashi Shinagawa
Shinagawa-ku
Tokyo 140-0002 Japan
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©

2016 Micro Motion, Inc. All rights reserved.

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